Pion absorption on He-4 into the ppd final state - art. no. 054604

Results from a 4 pi solid angle measurement of the reaction pi(+) + He-4--> ppd at incident pion energies of T-pi+=70, 118, 162, 239, and 330 MeV are p resented. Integrated cross sections are given for the final states with ene rgetic deuterons (ppd) and (pd)p. The differential cross sections are descr ibed by a complete set of five independent variables and various other kine matic variables and compared to cascade and phase space models where deuter ons were formed by a semiclassical pickup model. The data are investigated for signatures of initial and final state interactions: it is found that mo re than half of the (ppd) yield cannot be explained by these mechanisms. Th e remaining strength is reasonably well reproduced by 3N phase space models followed by pickup.